I don't know how has this happened... but everytime I try to enter my inventory the game crashes... I've been going fine for 15 levels, so I don't understand what has happened...
Can anybody help?

I've tryed uninstalling and reinstalling the game to no avail...

No help?

I haven't heard of anyone else running into such a bug, so I'm uncertain how to fix this.
Are you using a level cap remover/extender of some kind? Since you only encountered problems once you got to level 15, that seems a fair possibility. If you are, try removing the patch and see if it still crashes (though the game might not like this when you reload your save, resulting in more crashes).
If you don't have a cap remover, I'm out of ideas. Someone else may have some.

If I remove the level cap remover the save game stops working...
If I go back to an earlier save and go up to level 15 and beyond I don't find any bugs or crashes...
But that game is toasted >_<